Compositional dependence photoluminescence study of polycrystalline CuGaSe2 thin films

摘要

CuGaSe2 thin films with different Cu/Ga ratio were studied using photoluminescence (PL) method. Measurement at 1.4 K shows asymmetrically broadened PL spectra for all the samples where PL-peaks shift to lower energy with a decrease of the Cu/Ga ratio. Excitation power and temperature dependent PL spectra were explained using donor to acceptor pair transition under the influence of potential fluctuation. Magnitude of the potential fluctuation was calculated from lower energy tail of the emission spectra. Effect of Cu-deficiency on the properties of the CuGaSe2 films and fabricated solar cells were discussed in relation to the potential fluctuation at the band-edge.